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2 simple oscilliation problems. need help!

  1. Sep 20, 2004 #1
    1) You are a new employee at the Cut-Rate Cuckoo Clock company. The boss asks you what would happen to the frequency of the angular simple harmonic motion of the balance wheel if it had the same density and the same coil spring (thus the same torsion constant), but all the balance wheel dimensions were reduced by a factor of 2.56 to save material.

    a)You tell the boss (a) it is a dumb idea that will not work and (b) because the period will change by a factor of ?

    i use the formula t = 2pie x sqrt(L/M)
    then just change it to t = 2pie x sqrt(L/(1/2.56M))

    but i have trouble finding the ratio?

    b)By what factor must to the torsion constant be changed to make the smaller balance wheel oscillate at the same frequency?

    *need formula please

    2) A uniform circular disk whose radius R is 13.1 cm is suspended as a physical pendulum from a point on its rim. (The disk pivots about a loose-fitting nail driven through its face very close to the rim.) What is the period of oscillation?

    *need formula please!

    If you guys coudl just provide me with a clearers visual description and a dormula of what is happening I can do the math. Any help or suggestions are appreciated thank you!!
  2. jcsd
  3. Sep 20, 2004 #2


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    Science Advisor

    Where did you get this formula from? What is M? Do the units even work out?

    I'm not entirely sure what the system looks like, and seeing it makes a huge difference.

    Draw where the center of mass is, draw where the center of rotation is, then go at it from there.

    [tex]t = 2\pi \sqrt{\frac{L}{g}}[/tex]
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